3 files changed, 17 insertions, 18 deletions

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index cf61ecd148e0..21678464883a 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -280,7 +280,6 @@ struct svc_rqst {
         bool                    rq_splice_ok;   /* turned off in gss privacy
                                                  * to prevent encrypting page
                                                  * cache pages */
-        wait_queue_head_t       rq_wait;        /* synchronization */
         struct task_struct      *rq_task;       /* service thread */
 };
 
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 1db5007ddbce..ca8a7958f4e6 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -612,8 +612,6 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
         if (!rqstp)
                 goto out_enomem;
 
-        init_waitqueue_head(&rqstp->rq_wait);
-
         serv->sv_nrthreads++;
         spin_lock_bh(&pool->sp_lock);
         pool->sp_nrthreads++;
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 08e49d1e17b3..faaf2b46273b 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -348,8 +348,6 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
 
         cpu = get_cpu();
         pool = svc_pool_for_cpu(xprt->xpt_server, cpu);
-        put_cpu();
-
         spin_lock_bh(&pool->sp_lock);
 
         if (!list_empty(&pool->sp_threads) &&
@@ -382,10 +380,15 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
                         printk(KERN_ERR
                                 "svc_xprt_enqueue: server %p, rq_xprt=%p!\n",
                                 rqstp, rqstp->rq_xprt);
-                rqstp->rq_xprt = xprt;
+                /* Note the order of the following 3 lines:
+                 * We want to assign xprt to rqstp->rq_xprt only _after_
+                 * we've woken up the process, so that we don't race with
+                 * the lockless check in svc_get_next_xprt().
+                 */
                 svc_xprt_get(xprt);
+                wake_up_process(rqstp->rq_task);
+                rqstp->rq_xprt = xprt;
                 pool->sp_stats.threads_woken++;
-                wake_up(&rqstp->rq_wait);
         } else {
                 dprintk("svc: transport %p put into queue\n", xprt);
                 list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
@@ -394,6 +397,7 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
 
 out_unlock:
         spin_unlock_bh(&pool->sp_lock);
+        put_cpu();
 }
 
 /*
@@ -509,7 +513,7 @@ void svc_wake_up(struct svc_serv *serv)
                         svc_thread_dequeue(pool, rqstp);
                         rqstp->rq_xprt = NULL;
                          */
-                        wake_up(&rqstp->rq_wait);
+                        wake_up_process(rqstp->rq_task);
                 } else
                         pool->sp_task_pending = 1;
                 spin_unlock_bh(&pool->sp_lock);
@@ -628,7 +632,6 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
 {
         struct svc_xprt *xprt;
         struct svc_pool         *pool = rqstp->rq_pool;
-        DECLARE_WAITQUEUE(wait, current);
         long                    time_left;
 
         /* Normally we will wait up to 5 seconds for any required
@@ -654,15 +657,15 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
                         xprt = ERR_PTR(-EAGAIN);
                         goto out;
                 }
-                /* No data pending. Go to sleep */
-                svc_thread_enqueue(pool, rqstp);
-
                 /*
                  * We have to be able to interrupt this wait
                  * to bring down the daemons ...
                  */
                 set_current_state(TASK_INTERRUPTIBLE);
 
+                /* No data pending. Go to sleep */
+                svc_thread_enqueue(pool, rqstp);
+
                 /*
                  * checking kthread_should_stop() here allows us to avoid
                  * locking and signalling when stopping kthreads that call
@@ -676,14 +679,13 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
                         goto out;
                 }
 
-                add_wait_queue(&rqstp->rq_wait, &wait);
                 spin_unlock_bh(&pool->sp_lock);
 
                 time_left = schedule_timeout(timeout);
+                __set_current_state(TASK_RUNNING);
 
                 try_to_freeze();
 
-                remove_wait_queue(&rqstp->rq_wait, &wait);
                 xprt = rqstp->rq_xprt;
                 if (xprt != NULL)
                         return xprt;
@@ -786,10 +788,10 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
                 printk(KERN_ERR
                         "svc_recv: service %p, transport not NULL!\n",
                          rqstp);
-        if (waitqueue_active(&rqstp->rq_wait))
-                printk(KERN_ERR
-                        "svc_recv: service %p, wait queue active!\n",
-                         rqstp);
+
+        /* Make sure the task pointer is set! */
+        if (WARN_ON_ONCE(!rqstp->rq_task))
+                rqstp->rq_task = current_task;
 
         err = svc_alloc_arg(rqstp);
         if (err)